Method of making curved razor blades



June 5, 1928. 1, 12,516

J. E. DREW METHOD OF MAKING CURVED R AZOR' BLADES' Filed Aug. 21, 1926 iji- INVENTOR.

impracticable to recall jPatented June 5, 1928.

UNITED STATES mm a mmw, or mnsny our, NEW mam, Assmnon 'ro warm conronn'rxon, a conrona'rrox or j swam:

,ua'rnon or minus cunvnn nnzon was Application filed August'm, 1m. Serial No. 1ao,eao.

This invention relates to 'an improved method of making a curved blade for safety razors. v

' Man attempts to produce a perfect safety razor ave been made and many millions have been sold and passed into the possession of the public. One of the most popular type against which the blade was,c1amped. This; distance between cutting edge of blade and guard was sufiicient for shaving, purposes when the beard of the user was not too stiff; but in many cases of stiif beards, this distance was msuflicient to cause the cutting edge of the blade to bite the hair and shave,

Apparently, no attempt has been made through the ears to ascertain the best or most efiicient istance between the edge of such a razor blade and the guard, for it has; been found that different safety razors vary very much in this respect.

By experimentation and careful tests, it has now been discovered what the efficiency curve of safety razors is, 'and what change in new and existing razors or blades will increase the efficiency of such razors asshavin instruments. While the guard of new ss ety razors may be so constructed as to rovide this increased efficienc it is entirely an change the guards on the miliionsof razors already in possession of the public. The main object of the present invention is the production of a very simple and efficient method of maln'ng a curved replacement blade which,

when used either in a new razor or in any of the millions already in possession of the pubedge ofthe blade with respect to the lie, will automatically so position the cutting guard that the distance between said cutting edge and saidguard will represent the peak, or approximately the peak, of the efiiciency curve of the razor. Another object is the productic'n'i of a method of making a permanently curved replacement blade for safety edge of the blade being razors, the cutting These blades were approxisafety approximately.010" froman arcuate projection of its concave surface, so that when used in a new or old safety razor, the distance between its cuttin edge and said guard will be automatical y determined and W111 represent the peak, or substantially the peak, of the efliciency curve of 'the' razor. Vith these and other objects not specifically .mentioned in view, the invention consists in certain acts or ste s, and series of acts or steps, which will e hereinafter full described and then specifically set forth in the claims hereunto appended. 7

' In the accompanymg drawings, ,Fig. 1 is a 7 pers ective view of a blank which is the resu t of the first act or etc of the new method; Fi 2 is a sectiona view of two. bending an cooling dies between which the blank of Fig. 1, after heating to a temperin heat, is placed and simultaneously bent and cooled to permanently curve it without setting up internal strains, and to harden it; an Fig. '3 isillustrative ofthe step of the method in which cutting ed es are formed on the hard curved blade an locateda predetermined distance from an arcuate projection of the concavesurface of the blade in order to bring the 'cuttin ed es into such relationship with said surface t at when the blade is assembled with its holder, said ed es will be at the peak, or substantially at t e peak, of the efliciency curve of the-razor.

In carrying the invention into effect, a flat blank is first stamped from sheet steei. Such.

a blank is 'shown'in. Fig. 1 and marked 4. It i is reduced on an ordinar" punch press.

he blank is then heated to the usual tem pering heat in an ordinary heating furnace.

In order curved and hard and to produce from the heated blank. a permanently strained blade, the heated blankis then 571- "ultaneouslybent and cooled between dies and "6 each ofligwhich is'water' cooled by means of pipes? through which water is caused to" circulate by means not shown but of well known construction and operation. At the completion of this step of the method, the blank 4 will have become a blade havin a curved mid-section 8 and reversely curve edge-sections 9,9, the curvature being great- 1y exaggerated in the drawings in the intereat of clearness; Actually, the edge sections are reversely curved onlysufli'cie'nt y to cause their extreme edges that were bent from an arcuate projection of. the concave surface of the blade to lie approximate? .010" from said projection as'indicated in By thus bending the blank while it is cooling, all. internal stresses are absorbed, and

ghegesultant blade is unstrained as well as ar By bending the edge-sections away from the arcuate projection of the concave surface of the blade, a grinding operation is. eliminated and only one. is necessary, that one being on the convex side of the blade as indicated in Fig. 3 where two grmding wheels 10 are shown as in engagement with the edge-sections of the blade, to simultaneously grind the opposite cutting edges.

The next step is the honing of the ground ed es, and this is preferably done on both si es of the cutting ed es. And the final step is the stro ping'of t e honed edges, and this is prefera cutting edges. he honing and .stropping may be done by hand or by any suitable means or mechanism.

What is claimed is:

1. The method of making a curved razor blade, which consists in stamping a flat blank from sheet steel, then heating said blank to a temperin heat, then simultaneously bending an coolin the heated blank to produce a permanent y curved and hard and 'unstrained blade, then grinding ing the convex si a only ef saidblade to form cutting edges thereon, then honing both'sides -of the ground edges, and "then strapping both sides of the-honed edges.

- 3. The series of ste sin a method of making a'curv'ed razorb ade, which consists in heating a flat blank to a tempering heat, then simultaneously bendin and cooling the heated blank to reduce a ermanently curved and hard an unstrain dblade.

1% done on both sides of the curve its mid-section and reversely curve its edge-sections and thus produce a hard and unstrained reversely curved blade.

5. The series of steps in a method of 'making a curved razor blade, which consists in heating a flat blank to a tempering heat, then simultaneously bending and cooling the heated blank to harden and permanently curve its mid-section and reversely curve .its edge-sections and thus produce a hard and unstrained reversely curved blade, the curvature of said blade being such that opposite edges of the .blade he approximately .010" from an arcuate projection of the concave surface of the blades mid-section.

Y 6. The series of ste in a method of making a curved razor b ade, which consists in heating a flat blank to a tempering heat, thensimultaneously bending and cooling the heated blank to produce a permanently curved and hard and unstrained blade, then grinding said blade to form cutting edges thereon.

5 7. The series of ste s in a method of mak ing a curved razor b ade, which consists in heating a flat blank to'a tempering heat, then simultaneously bending and cooling theheated blank to harden and permanently curve its mid-section and reversely curve its edge-sections and thus form a hard and unstrained reversely curved blade, then grinding the convex side only of said blade to form cutting edges thereon.

8. The series of steps in a method of mak ing'a curved razor blade, which consists in heating a flat blank to a temperingheat, then simultaneously bending and cooling the heated blank to harden and permanently curve its mid-section and reversely curve its edge-sections and thus form a hard and unstfained reversely curved blade, then grinding the convex side only of said blade to form cutting edges thereon then hom'ng both sides of the ground ed stropping both sides of the honed edges.

gas, and then In testimony whereof, I have signed my I name to this specification.

"JOHN 'E. DREW. 

